This only works if your previous firmware version was 9.00. If you updated from 12.00 to 13.02, you could only revert back to 12.00. 2. Game Downgrading (Software Only)
Software is used to manipulate the data so the console boots from the inactive slot containing the older firmware. Reassemble & Test ps4 downgrade 1302 to 900
You must have a backup of your console's unique Syscon and NOR flash memory from when it was previously on version 9.00. This only works if your previous firmware version was 9